Abstract：Using the repeated measurement data from Hainan island mobile gravity survey network of 13 periods from 2016 to 2022, we analyze the dynamic changes of differential gravity field and cumulative gravity field in the study area, and emphatically analyze the spatial and temporal changes of gravity field in the southwest of Hainan island before and after the Sanya MS4.2 earthquake on August 20, 2019. The results show that before 2 and 3 years of Sanya MS4.2 earthquake, in the area near the epicenter of the Sanya MS4.2 earthquake a gradient zone of cumulative change of gravity field appears, the anomaly range of gravity variation gradient zone before the earthquake is 60 km, and the maximum variation of gravity field is about 60 μGal. After the Sanya MS4.2 earthquake, the gravity field in the area near the epicenter continued to rise and began to decline in coordination until the second half of 2020. During the decline, a swarm event occurred with the Ledong 3.2 earthquake on August 8, 2021 as the largest earthquake. The wavelet multi-scale decomposition of the dynamic changes of the cumulative gravity field in Hainan island from September 2016 to August 2019 shows that the gravity field changes in southwest Hainan island are abnormal in the third, fourth and fifth order wavelet detail maps.
LI Sheng,HUANG Zhangrong,HU Jiuchang et al. Gravity Field Changes in Hainan Island before and after Sanya MS4.2 Earthquake and Its Wavelet Multiscale Decomposition[J]. jgg, 2023, 43(9): 945-949.
